Acetamidobenzamide compounds for neurodegenerative disorders

ABSTRACT

A group of benzamide compounds are disclosed which are useful for treating neurodegenerative disorders. Methods for making these compounds are provided. These materials are formed into pharmaceutical compositions for oral or intravenous administration to patients suffering from conditions such as Parkinson&#39;s disease which can exhibit themselves as progressive loss of central nervous system function. The compounds can arrest or slow the progressive loss of function.

This application is a CON of Ser. No. 10/319,371, filed on Dec. 12,2002, now U.S. Pat. No. 6,759,433,

-   which is DIV of Ser. No. 09/846,060, filed on Apr. 30, 2001, now    U.S. Pat. No. 6,509,378,-   which is CON of Ser. No. 09/512,388, filed on Feb. 25, 2000, now    abandoned,-   which is CON of Ser. No. 09/050,744, filed on Mar. 30, 1998, now    U.S. Pat. No. 6,066,765,-   which is DIV of Ser. No. 08/812,138, filed on Mar. 6, 1997, now U.S.    Pat. No. 5,756,548,-   which is CON of Ser. No. 08/415,677, filed on Apr. 3, 1995, now    abandoned.

FIELD OF THE INVENTION

This invention concerns benzamide compounds, pharmaceutical compositionscontaining these compounds, and their use to treat or protect againstneurodegenerative conditions.

BACKGROUND INFORMATION

Neurodegenerative disease encompasses a range of seriously debilitatingconditions including Parkinson's disease, amyotrophic lateral sclerosis(ALS, “Lou Gehrig's disease”), multiple sclerosis, Huntington's disease,Alzheimer's disease, diabetic retinopathy, multi-infarct dementia,macular degeneration and the like. These conditions are characterized bya gradual but relentless worsening of the patient's condition over time.The mechanisms and causes of these diseases are becoming betterunderstood and a variety of treatments have been suggested. One of theseneurodegenerative conditions, Parkinson's disease, is associated withabnormal dopamine depletion in selected regions of the brain.

Recent summaries of the state of understanding of Parkinson's diseaseare provided by Marsden, C. D., in “Review Article—Parkinson's Disease”Lancet (Apr. 21, 1990) 948–952 and Calne, D. B., in “Treatment ofParkinson's Disease” NEJM (Sep. 30, 1993) 329: 1021–1027. As thesereviews point out, dopamine deficiency was identified as a keycharacteristic of Parkinson's disease, and the destruction of thedopaminergic nigrostriatal pathway paralleled dopamine depletion inParkinson's patients.

Rapid development of Parkinson's-like symptoms in a small population ofillicit drug users in the San Jose, Calif. area was lined to traceamounts of a toxic impurity in the home-synthesized drugs. Subsequentstudies in animal models, including monkeys, demonstrated that1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPT) was the cause of theParkinson's-like symptoms which developed in the illicit drug users, asreported by J. W. Langston et al., in “Chronic Parkinsonism in HumansDue to a Product of Meperidine-Analog Synthesis” Science (Feb. 25, 1983)219, 979–980. These early findings and the many studies that theystimulated led to the development of reliable models for Parkinson'sdisease, as reported by Heikkila, R. E., et al., in “DopaminergicNeurotoxicity of 1-Methyl-4-Phenyl-1,2,5,6-Tetrahydropyridine in Mice”Science (Jun. 29, 1984) 224:1451–1453; Burns, R. S., et al., in “APrimate Model of Parkinsonism . . . ” Proc. Natl. Acad. Sci USA (1983)80:4546–4550; Singer, T. P., et al., “Biochemical Events in theDevelopment of Parkinsonism . . . ” J. Neurochem. (1987) 1–8; andGerlach, M. et al., “MPTP Mechanisms of Neurotoxicity and theImplications for Parkinson's Disease” European Journal of Pharmacology(1991) 208:273–286. These references and others describe studies to helpexplain the mechanism of how the administration of MPTP to animals givesrise to motor defects characteristic of Parkinson's disease. Theyclearly indicate that MPTP was the cause of the Parkinson's-likesymptoms that developed in the humans who had used the tainted illicitdrugs and that similar motor deficits were found in other primates andother test animals which had been dosed directly with MPTP. They furtherpoint out that the administration of MPTP induces a marked reduction inthe concentration of dopamine in the test subjects.

These findings have led to the development of an assay for agentseffective in treating dopamine-associated neurodegenerative disorders,such as Parkinson's disease. In this assay, test animals are given anamount of MPTP adequate to severely depress their dopamine levels. Testcompounds are administered to determine if they are capable ofpreventing the loss of dopamine in the test animals. To the extent thatdopamine levels are retained, a compound can be considered to be aneffective agent for slowing or delaying the course of neurodegenerativedisease, e.g., Parkinson's disease.

Mitochondrial function is associated with many neurodegenerativediseases such as ALS, Huntington's disease, Alzheimer's disease,cerebellar degeneration, and aging itself (Beal, M. F. in MitochondrialDysfunction and Oxcidative Damage in Neurodegenerative Diseases, R. G.Landes Publications Austin, Tex., 1995 at, for example, pages 53–61 and73–99). Mitochondrial damage is the mechanism by which MPTP depletesdopamine concentrations in the striatum (Mizuno, Y., Mori, H., Kondo, T.in “Potential of Neuroprotective Therapy in Parkinson's Disease” CNSDrugs (1994) 1:45–46). Thus, an agent which protects from mitochondrialdysfunction caused by MPTP could be useful in treating diseases of thecentral nervous system in which the underlying cause is mitochondrialdysfunction.

While other benzamide compounds are known, their utility heretofore hasgenerally been as intermediates in chemical syntheses or in fieldsunrelated to the present invention. Slight structural changes yieldedlarge differences in efficacy and toxicity. The vast majority ofbenzamide compounds have little or no activity in our screens. However,there are reports of biological activity for other, structurallydifferent benzamides. These reports include:

El Tayar et al., “Interaction of neuroleptic drugs with rat striatal D-1and D-2 dopamine receptors: a quantitative structure—affinityrelationship study” Eur. J. Med. Chem. (1988) 23:173–182;

Monković et al., “Potential non-dopaminergic gastrointestinal prokineticagents in the series of substituted benzamides” Eur. J. Med. Chem.(1989) 24:233–240;

Banasik et al., “Specific inhibitors of poly(ADP-Ribose) synthetase andmono(ADP-ribosyl)transferase” J. Biol. Chem. (1992) 267:1569–1575;

Bishop et al., “Synthesis and in vitro evaluation of2,3-dimethoxy-5-(fluoroalkyl)-substituted benzamides: high-affinityligands for CNS dopamine D₂ receptors” J. Med. Chem. (1991) 34:1612–1624;

Höberg et al., “Potential antipsychotic agents. 9. Synthesis andsteroselective dopamine D-2 receptor blockade of a potent class ofsubstituted (R)-(N-[benzyl-2-pyrrolidinyl)methyl]benzamides. Relationsto other side chain congeners” J. Med. Chem. (1991) 34:948–955;

Katopodis et al., “Novel substrates and inhibitors of peptidylglycineα-amidating monooxygenase” Biochemistry (1990) 29:4541–4548; and

Rainnie et al., “Adenosine inhibition of mesopontine cholinergicneurons: implications for EEG arousal” Science (1994) 26:689–690.

Other benzamide-containing pharmaceutical compositions and their use totreat or protect against neurodegenerative conditions were disclosed incommonly owned U.S. patent application Ser. No. 08/227,777 filed Apr.14, 1994, the disclosure of which is incorporated herein by reference inits entirety.

STATEMENT OF THE INVENTION

It has now been found that a family of novel acetamidobenzamidecompounds of the Formula I below exhibit strong activity againstParkinson's disease as measured by their ability to prevent MPTP-inducedreduction of dopamine levels.

where R′ is a straight, branched or cyclic saturated alkyl of from 3 to5 carbon atoms and n is 1 or 2.

It has also been found that the novel nitro- and aninobenzamidecompounds N-tert-amyl-4-nitrobenzamide (CPI1033),N-1,2-dimethylpropyl-4-nitrobenzamide (CPI1085),N-n-butyl-3-nitrobenzamide (CPI1135), N-n-pentyl-4-nitrobenzamide(CPI1140), N-2-methylbutyl-4-nitrobenzamide (CPI1146),N-n-butyl-3,5-dinitrobenzamide (CPI1147),N-methylcyclopropyl-4-nitrobenzamide (CPI1164),N-n-butyl-2-nitrobenzamide (CPI1173), N-n-pentyl-2-nitrobenzamide(CPI1174), and N-methylcyclopropyl-4-aminobenzamide (CPI1240) are usefulas intermediates for preparing the acetamide compounds of Formula Iabove and as pharmaceutical agents.

These nitro- and aminobenzamide compounds and the acetamidobenzamidecompounds of Formula I constitute one aspect of the invention.

The invention can also take the form of pharmaceutical compositionsbased on one or more of the compounds of Formula II below:

where R′ is a saturated alkyl of from 3 to 5 carbon atoms, each R isindependently —NH—CO—CH₃, —NO₂ or —NH₂, and n is 1 or 2, with thefollowing provisos: 1) when n is 1 and R is —NO₂ at the 4 position ofthe ring, R′ is not tert-butyl, iso-butyl, or propyl; 2) when n is 1 andR is —NO₂ at the 2 position of the ring, R′ is not iso-butyl or propyl;and 3) when n is 2 and R′ is tert-butyl and both Rs are —NO₂, the Rgroups are not at the 3 and 5 positions of the ring.

The invention can further take the form of methods of treatingneurodegenerative conditions using these materials.

Thus, in one aspect this invention provides the novel acetamidobenzamidecompounds of the Formula I and the novel nitro- and aminobenzamidesdescribed above.

In another aspect this invention provides pharmaceutical compositionswhich include one or more benzamide compounds of the Formula II in apharmaceutically acceptable carrier. This carrier is preferably an oralcarrier but can be an injectable carrier as well. These pharmaceuticalcompositions can be in bulk form but more typically are presented inunit dosage form.

In another aspect this invention provides a method for treating apatient suffering from a dopamine-associated neurodegenerativecondition. This method involves administering to the patient aneffective neurodegenerative condition-treating amount of one or more ofthe pharmaceutical compositions just described.

In another aspect this invention provides a method for treating apatient suffering from a condition characterized by progressive loss ofcentral nervous system function. This method involves administering, tothe patient with loss of central nervous system function an effectiveamount of one or more of the pharmaceutical compositions just described.

In a most important aspect this invention provides a method for treatinga patient suffering from a progressive loss of central nervous systemfunction associated with Parkinson's disease. This method involvesadministering (preferably orally) to the patient with loss ofprogressive central nervous system function an effective amount of oneor more of the pharmaceutical compositions just described.

In another aspect this invention provides a method for treating apatient suffering from a condition characterized by progressive loss ofnervous system function due to mitochondrial dysfunction. This methodinvolves administering to the patient with loss of central nervoussystem function an effective amount of one or more of the pharmaceuticalcompositions just described.

In a further aspect, this invention provides methods for preparing thecompounds of Formula I and II. These methods generally involvecondensing an alkyl amine of from 3 to 5 carbon atoms with a mono ordinitro benzoyl halide having the nitro configuration corresponding tothe nitro, amine or acetamide substitution desired in the finalcompound, optionally, reducing the nitro groups, and, optionally,converting the amino benzamides to acetoamidobenzamides by reaction withan acetylhalide.

DETAILED DESCRIPTION OF THE INVENTION

The Compounds

This invention provides novel acetamidobenzamide compounds of theFormula I below and their use as active pharmaceutical agents.

where R′ is a saturated alkyl of from 3 to 5 carbon atoms and n is 1 or2.

The acetamido group may be found anywhere on the ring. Preferredembodiments include when n is 1 and the R group is at the 2, 3 or 4position of the ring and when n is 2 and the R groups are at the 2 and3, 2 and 4, 2 and 5, 2 and 6, 3 and 4, or 3 and 5 positions of the ring.

With respect to the alkyl substituents, compounds wherein R′ is an alkylwhich does not have a hydrogen on the alpha carbon, that is, the carbonwhich bonds to the nitrogen of the ring, are preferred. Examples ofthese preferred R′ groups are tert-butyl and tert-amyl.

The benzamide of the Formula I above which is N-tert-butyl4-acetamidobenzamide is referred to elsewhere in this specification by theinternal compound designation number CPI1189.

The benzamide of the Formula I above which isN-iso-propyl-4-acetamidobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1232.

The benzamide of the Formula I above which isN-tert-amyl-4-acetamidobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1233.

The benzamide of the Formula I above which isN-tert-butyl-3-acetamidobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1234.

The benzamide of the Formula I above which isN-methylcyclopropyl-4-acetamidobenzamide is referred to elsewhere inthis specification by the internal compound designation number CPI1241.

The compounds N-tert-butyl 4-acetamidobenzamide (CPI1189),N-iso-propyl-4-acetamidobenzamide (CPI1232),N-tert-amyl-4-acetamidobenzamide CPI1233),N-tert-butyl-3-acetamidobenzamide (CPI1234), andN-methylcyclopropyl-4-acetamidobenzamide (CPI1241) are the mostpreferred compounds of the Formula I at this time.

The invention also provides the following novel nitro- andaminobenzamide compounds which are useful both as intermediates inpreparing the compounds of the Formula I and as active pharmaceuticalagents: N-tert-amyl-4-nitrobenzamide (CPI1033),N-1,2-dimethylpropyl-4-nitrobenzamide (CPI1085),N-n-butyl-3-nitrobenzamide (CPI1135), N-n-pentyl-4-nitrobenzamide(CPI1140), N-2-methylbutyl-4-nitrobenzamide (CPI1146),N-n-butyl-3,5-dinitrobenzamide (CPI1147),N-methylcyclopropyl-4-nitrobenzamide (CPI1164),N-n-butyl-2-nitrobenzamide (CPI1173), N-n-pentyl-2-nitrobenzamide(CPI1174), and N-methylcyclopropyl-4-aminobenzamide (CPI1240).

The benzamide which is N-tert-amyl-4-nitrobenzamide is referred toelsewhere in this specification by the internal compound designationnumber CPI1033.

The benzamide which is N-1,2-dimethylpropyl-4-nitrobenzamide is referredto elsewhere in this specification by the internal compound designationnumber CPI1085.

The benzamide which is N-n-butyl-3-nitrobenzamide is referred toelsewhere in this specification by the internal compound designationnumber CPI1135.

The benzamide which is N-n-pentyl-4-nitrobenzamide is referred toelsewhere in this specification by the internal compound designationnumber CPI1140.

The benzamide which is N-2-methylbutyl-4-nitrobenzamide is referred toelsewhere in this specification by the internal compound designationnumber CPI1146.

The benzamide which is N-n-butyl-3,5-dinitrobenzamide is referred toelsewhere in this specification by the internal compound designationnumber CPI1147.

The benzamide which is N-methylcyclopropyl-4-nitrobenzamide is referredto elsewhere in this specification by the internal compound designationnumber CPI1164.

The benzamide which is N-n-butyl-2-nitrobenzamide is referred toelsewhere in this specification by the internal compound designationnumber CPI1173.

The benzamide which is N-n-pentyl-2-nitrobenzamide is referred toelsewhere in this specification by the internal compound designationnumber CPI1174.

The benzamide which is N-methylcyclopropyl-4-aminobenzamide is referredto elsewhere in this specification by the internal compound designationnumber CPI1240.

When the benzamide compound contains an amino group, such as CPI 1240,this functionality can be present as such or as a pharmaceuticallyacceptable salt. When these “compounds” are referred to it is to beunderstood that these salts are included as well.

Commonly owned U.S. patent application Ser. No. 08/227,777, referred toabove, discloses several benzamides useful in treating neurodegenerativediseases based on their protective action in the MPTP mouse model ofParkinson's disease. The compound N-tert-butyl 4-acetamidobenzamide(CPI1189) of the present invention is an in vivo biotransformationproduct of one of these benzamides (N-tert-butyl 4-nitrobenzamide(CPI1020)) which is found in the blood of rats and mice to which CPI1020has been administered orally. This compound is likely formed in the bodyby reduction of the ring nitro of CPI1020 to an amino moiety (CPI1160)followed by acetylation of the amino function.

The compounds of the present invention, as exemplified by CPI1189, aremuch more potent than CPI1020 (approximately 10 times as potent) inprotecting mice from dopamine reduction in the striatum induced by s.c.treatment with MPTP. Based on structurally similar molecules such asacetaminophen which contain an acetamido functionality, they should alsobe safer than CPI1020 because they would not be metabolized in the bodyto result in metabolites containing hydroxylamines likely to be Amespositive) nor would they be likely to result in amino metabolites whichmay have cardiovascular and/or anorexic effects.

Pharmaceutical Compositions

The benzamide compounds of the Formula II below:

where R′ is a straight or branched chain saturated alkyl of from 3 to 5carbon atoms, each R is independently —NH—CO—CH₃, —NO₂ or —NH₂, and n is1 or 2, with the following provisos: 1) when n is 1 and R is —NO₂ at the4 position of the ring, R′ is not tert-butyl, iso-butyl, or propyl; 2)when n is 1 and R is —NO₂ at the 2 position of the ring, R′ is notiso-butyl or propyl; and 3) when n is 2 and R′ is tert-butyl and both Rsare —NO₂, the R groups are not at the 3 and 5 positions of the ring, areformulated into pharmaceutical compositions suitable for oral or otherappropriate routes of administration.

The benzamide of the Formula II above which isN-iso-propyl-4-nitrobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1026.

The benzamide of the Formula II above which isN-tert-butyl-3-nitrobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1034.

The benzamide of the Formula II above which isN-tert-butyl-2-nitrobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1035.

The benzamide of the Formula II above which isN-n-butyl-4-nitrobenzamide is referred to, elsewhere in thisspecification by the internal compound designation number CPI1045.

The benzamide of the Formula II above which isN-n-propyl-4-nitrobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1047.

The benzamide of the Formula II above which isN-tert-butyl-3,5-dinitrobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1049.

The benzamide of the Formula II above which isN-1-methylpropyl-4-nitrobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1084.

The benzamide of the Formula II above which isN-tert-butyl-4-aminobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1160.

The benzamide of the Formula II above which isN-tert-butyl-3-aminobenzamide is referred to elsewhere in thisspecification by the internal compound designation number CPI1248.

When R is —NH₂, the compounds of the Formula II may be used as salts inwhich the amine group is protonated to the cation form, in combinationwith a pharmaceutically acceptable anion, such as chloride, bromide,iodide, hydroxyl, nitrate, sulfonate, methane sulfonate, acetate,tartrate, oxalate, succinate, or palmoate.

Pharmaceutical compositions using the compounds N-tert-butyl4-acetamidobenzamide (CPI1189), N-tert-butyl-3-acetamidobenzamide(CPI1234), N-tert-amyl-4-acetamidobenzamide (CPI1233),N-tert-butyl-4-aminobenzamide (CPI1160), N-tert-butyl-3-nitrobenzamide(CPI1034), and N-tert-butyl-3-aminobenzamide (CPI1248) are mostpreferred at this time.

The compositions for oral administration can take the form of bulkliquid solutions or suspensions, or bulk powders. More commonly,however, the compositions are presented in a unit dosage form tofacilitate accurate dosing. Typical unit dosage forms include prefilled,premeasured ampules or syringes of the liquid compositions or pills,tablets, capsules or the like in the case of solid compositions. In suchcompositions, the benzamide compound is usually a minor component (0.1to say 50% by weight or preferably from about 1 to about 40% by weight)with the remainder being various vehicles or carriers and processingaids helpful for forming the desired dosing form. A liquid form mayinclude a suitable aqueous or nonaqueous vehicle with buffers,suspending and dispensing agents, colorants, flavors and the like.

A solid form may include, for example, any of the following ingredients,or compounds of a similar nature: a binder such as microcrystallinecellulose, gum tragacanth or gelatin; an excipient such as starch orlactose, a disintegrating agent such as alginic acid, Primogel, or cornstarch; a lubricant such as magnesium stearate; a glidant such ascolloidal silicon dioxide; a sweetening agent such as sucrose orsaccharin; or a flavoring agent such as peppermint, methyl salicylate,or orange flavoring.

In the case of injectable compositions, they are commonly based uponinjectable sterile saline or phosphate-buffered saline or otherinjectable carriers known in the art. Again the active benzamide istypically a minor component, often being from about 0.05 to 10% byweight with the remainder being the injectable carrier and the like.

These components for orally administrable or injectable compositions aremerely representative. Other materials as well as processing techniquesand the like are set forth in Part 8 of Remington's PharmaceuticalSciences, 17th edition, 1985, Mack Publishing Company, Easton, Pa.,which is incorporated by reference.

One can also aduminister the compounds of the invention in sustainedrelease forms or from sustained release drug delivery systems. Adescription of representative sustained release materials can be foundin the incorporated materials in Remington's Pharmaceutical Sciences.

Conditions Treated and Treatment Regimens

The conditions treated with the benzamide-containing pharmaceuticalcompositions may be classed generally as neurodegenerative conditions.These include conditions characterized by protracted low grade stressupon the central nervous system and gradual progressive loss of centralnervous system function. These conditions include Parkinson's disease,amyotrophic later sclerosis (ALS, “Lou Gehrig's disease”), multiplesclerosis, Huntington's disease, Alzheimer's disease, diabeticretinopathy, multi-infarct dementia, macular degeneration and the like.Each of these conditions is characterized by a progressive loss offunction. The benzamide compound-containing pharmaceutical compositionsof this invention, when administered orally or by injection such asintravenously, can slow and delay and possibly even to some extentreverse the loss of function.

Injection dose levels for treating these conditions range from about 0.1mg/kg/hour to at least 10 mg/kg/hour, all for from about 1 to about 120hours and especially 24 to 96 hours. A preloading bolus of from about0.1 mg/kg to about 10 mg/kg or more may also be administered to achieveadequate steady state levels. The maximum total dose is not expected toexceed about 2 g/day for a 40 to 80 kg human patient.

With these neurodegenerative conditions, the regimen for treatmentusually stretches over many months or years so oral dosing is preferredfor patient convenience and tolerance. With oral dosing, one to five andespecially two to four and typically three oral doses per day arerepresentative regimens. Using these dosing patterns, each dose providesfrom about 1 to about 20 mg/kg of benzamide, with preferred doses eachproviding from about 1 to about 10 mg/kg and especially about 1 to about5 mg/kg.

Of course, one can administer the benzamide compound as the sole activeagent or one can administer it in combination with other agents,including other active benzamide compounds.

Methods of Preparation of Compounds

The benzamide compounds of this invention can be prepared using commonlyavailable starting materials and readily achievable reactions.

One representative preparation route, which is illustrated withtert-butyl amine, but which may be used with any alkyl amine, involvesthe following reactions:

where X is halo such as I, Br, F or Cl.

In step (A) the N-tert-butyl nitrobenzamides (III) are formed. Thisreaction must be carried out at temperatures below 10° C.

This step (A) yields as benzamides III, the compounds of the inventionwhere R is —NO₂.

In step (B) the nitro groups in the mono- or di-nitro benzamide III aresubjected to reduction. This is commonly carried out with a reducingagent such as hydrazine and an appropriate catalyst such as aheterogeneous platinum, iron oxide hydroxide, palladium or nickelcatalyst, typically on a support, or with hydrogen gas and a catalyst.

This step (B) yields as benzamides IV, the compounds of the inventionwhere R is NH₂.

In step (C) the amino-benzamides IV are converted to acetamidobenzamidesV by reaction with an acetyl halide such as acetylchloride. Thisreaction is carried out in the presence of a mild base and at low toambient temperatures such as −20° C. to +20° C. This yields thecompounds of the invention where R is acetamido.

Alternate synthetic schemes may also be used to prepare the compounds ofthe present invention. Examples of these alternate routes are set forthbelow using CPI1189 as the representative compound. Other compounds maybe prepared using these alternate methods by starting with appropriatestating materials, such as 2- or 3- amino- or nitro-benzonitrile or2,3-, 2,4, 2,5-, 2,6-, 3,4- or 3,5-diamino- or dinitro-benzonitrile andthe appropriate alcohol (Alternate Route 1) or similarly substitutedtoluene compounds and the appropriate alkyl amine (Alternate Route 3).

Alternate Route 1

This route begins with acetylation of, for example, 4-aminobenzonitrile(A) to compound (B) using standard methods. Acid hydrolysis oftert-butanol in the presence of 4-acetamidobenzonitrile (B), provides afeasible synthetic pathway to CPI1189.

Alternate Route 2

Acetylation, using standard methods, of the inexpensive startingmaterial PABA (C) affords a cheap method to produce 4-acetamidobenzoicacid (D). Conversion of (D) to the acid chloride (E) using standardmethods (e.g., SOCl₂) and subsequent amidation using standard methods,such as those described previously, produces CPI1189 from inexpensiveraw materials.

Alternate Route 3

Another method for the preparation of the compounds of the presentinvention begins with acetylation, using standard methods, of, forexample, paratoluidine (F) to 4-acetamidotoluene (G). The syntheticintermediate (G) may be converted to 4-acetamidobenzoic acid (D) withcommon oxidizing agents (e.g., KMnO₄) and subsequently transformed toCPI1189 as outlined in Alternate Route 2.

EXAMPLES

The invention will be further described by the following Examples. Theseare provided to illustrate several preferred embodiments of theinvention but are not to be construed as limiting its scope which is,instead, defined by the appended claims. Examples 1 to 19 demonstratethe preparation of acetamidobenzamides, as well as nitro- andaminobenzamides, which are representative of the benzamide compoundsemployed in the compositions and methods of this invention. Examples 20to 24 demonstrate the preparation of pharmaceutical compositions basedon the compounds. Thereafter biological test results illustrating theactivity of the compositions of the invention are provided.

Example 1 Preparation of N-tert-butyl-4-aminobenzamide (CPI1160)

tert-Butyl amine (14.6 g, 0.200 mole) was stirred in ethyl acetate (150mL, purified by washing with 5% sodium carbonate solution, saturatedsodium chloride solution, drying over anhydrous magnesium sulfate, andfiltering through fluted filter paper) and cooled to 5° C. with an icebath. 4-nitrobenzoyl chloride (18.6 g, 0.100 mole) in purified ethylacetate (75 mL) was added dropwise at such a rate to maintain thetemperature below 10° C. The ice bath was removed upon complete additionof benzoyl chloride solution and the reaction stirred for 4 hours. Thereaction mixture was then filtered on a Büchner funnel, the filtratewashed three times with 5% HCl, once with saturated sodium chloride,dried over anhydrous magnesium sulfate, filtered through fluted filterpaper, and the solvent stripped off leaving white crystalline product.The product was dried in a vacuum oven at 24 mm and 45° C. for 14 hours.This procedure produced 17.13 g of crystals ofN-tert-butyl-4-nitrobenzamide (CPI1020) (77% yield), mp 162–163° C.Proton nuclear magnetic resonance (89.55 MHz in CDCl₃) showedabsorptions at 8.257 ppm (d, 8.8 Hz, 2H; 3,5-aryl H); 7.878 ppm (d, 8.8Hz, 2H; 2,6-aryl H); 6.097 ppm (bs, 1H; N—H); 1.500 ppm (s, 9H;tert-butyl H).

Palladium on carbon (5%, 75 mg) was added to CPI-1020 (5 g, 22.5 mmole)in 95% ethanol at 55° C. A solution of hydrazine (1.2 mL) in 95% ethanol(10 mL) was added dropwise over 30 min. and more Pd/C added (75 mg). Thereaction was refluxed 3 hours, hydrazine (0.5 g) in 95% ethanol (5 mL)was added and the reaction was refluxed for another hour. The reactionwas filtered on a buchner funnel, the volume of solvent reduced undervacuum, and extracted with dichloromethane. The combined extracts weredried over magnesium sulfate and solvent stripped, leaving 3.90 g ofN-tert-butyl-4-aminobenzamide (CPI1160) (90% yield), melting point125–127° C. 90 MHz proton NMR (in CDCl₃) showed absorbances at 7.290 ppm(2H, d, 8.8 Hz; 2,6 aryl H); 6.368 ppm (2H, d, 8.8 Hz; 3,5 aryl H); 5.45ppm (1H, bs; NHC═O); 3.727 ppm (2H, bs; aryl-NH₂); 1.186 ppm (9H, s;t-butyl H).

Example 2 Preparation of N-tert-butyl-4-acetamidobenzamide (CPI1189)

Acetyl chloride (0.45 g, 5.7 mmole) in ethyl acetate (25 mL) was addeddropwise to CPI-1160 (1.0 g, 5.2 mmole) and triethyl amine (0.58 g, 5.7mmole) in ethyl acetate at 3° C. at such a rate to maintain thetemperature below 10° C. The reaction was allowed to warm to roomtemperature, stirred 1 hour, and washed with 5% HCl. Recrystallizationfrom acetone gave 1.08 g N-tert-butyl-4-acetamidobenzamide (CPI1189)(89%yield), melting point 119–121° C. 90 MHz proton NMR (in DMSO-d6) showedabsorbances at 9.726 ppm (1H, bs, N—H); 7.715 ppm (4H, dd, 4.4 Hz; arylH); 7.295 ppm (1H, bs; NH); 2.844 ppm (3H, s; CH₃CO); 1.448 ppm (9H, s;t-butyl H).

Example 3 Preparation of N-tert-butyl-3-acetamidobenzamide (CPI1234)

The amidation procedures of Example 1 were followed using 3-nitrobenzoylchloride instead of 4-nitrobenzoyl chloride. This gaveN-tert-butyl-3-nitrobenzamide (CPI1034) in 92% yield, melting point123–125° C. Proton NMR (in CDCl₃) showed absorptions at 8.517 ppm(2-aryl H, s, 1H); 8.337 ppm (4-aryl H, d, 8.8 Hz, 1H); 8.121 ppm (6arylH, d, 6.4 Hz, 1H); 7.618 ppm (5-aryl H, m, 1H); 6.032 ppm (N—H, bs, 1H);1.484 ppm (t-butyl H, s, 9H).

Iron (III) oxide hydroxide catalyzed hydrazine reduction producedN-tert-butyl-3-aminobenzamide (CPI1248) in 53% yield, melting point118–120° C. Proton NMR (in CDCl₃) showed absorbances at 7.088 ppm(4–6-aryl H, m, 3H); 6.794 ppm (2-aryl H, s, 1H); 5.902 ppm (N—H, bs,1H); 3.145 ppm (aryl N—H, bs, 2H); 1.458 ppm (t-butyl H, s, 9H).

Acetylation of CPI1248 as described in Example 2 gaveN-tert-butyl-3-acetamidobenzamide (CPI1234) in 75% yield, melting point194–195° C. Proton NMR (in CDCl₃) showed absorptions at 7.778 ppm(4–6-aryl H, m, 3 H); 7.392 ppm (2-aryl H, s, 1H); 6.08 ppm (N—H, bs,1H); 2.174 ppm (acetyl CH₃, s, 9H); 1.500 ppm (t-butyl H, s, 9H).

Example 4 Preparation of N-tert-butyl-2-acetamidobenzamide

The method of Example 3 is repeated using 2-nitrobenzoyl chloride in theamidation step. This yields N-tert-butyl-2-nitrobenzamide (CPI1035).

Reduction of the nitrobenzamide with hydrazine yieldsN-tert-butyl-2-aminobenzamide.

Acetylation of the aminobenzamide yieldsN-tert-butyl-2-acetamidobenzamide.

Example 5 Preparation of N-iso-propyl-4-acetamidobenzamide (CPI1232)

The method of Example 3 is repeated using 4-nitrobenzoyl chloride andiso-propyl amine in the amidation step. This yieldsN-iso-propyl-4-nitrobenzamide (CPI1026).

Reduction of the nitrobenzamide with hydrazine yieldsN-iso-propyl-4-aminobenzamide.

Acetylation of the aminobenzamide yieldsN-iso-propyl-4-acetamidobenzamide (CPI1232).

Example 6 Preparation of N-tert-amyl-4-acetamidobenzamide (CPI1233)

The method of Example 3 is repeated using 4-nitrobenzoyl chloride andtert-amyl amine in the amidation step. This yieldsN-tert-amyl-4-nitrobenzamide (CPI1033).

Reduction of the nitrobenzamide with hydrazine yieldsN-tert-amyl-4-aminobenzamide.

Acetylation of the aminobenzamide yieldsN-tert-amyl-4-acetamidobenzamide (CPI1233).

Example 7 Preparation of N-iso-butyl-4-acetamidobenzamide

The method of Example 3 is repeated using 4-nitrobenzoyl chloride andiso-butyl amine in the amidation step. This yieldsN-iso-butyl-4-nitrobenzamide (CPI1044).

Reduction of the nitrobenzamide with hydrazine yieldsN-iso-butyl-4-aminobenzamide.

Acetylation of the aminobenzamide yieldsN-iso-butyl-4-acetamidobenzamide.

Example 8 Preparation of N-n-butyl-4-acetamidobenzamide

The method of Example 3 is repeated using 4-nitrobenzoyl chloride andn-butyl amine in the amidation step. This yieldsN-n-butyl-4-nitrobenzamide (CPI1045).

Reduction of the nitrobenzamide with hydrazine yieldsN-n-butyl-4-aminobenzamide.

Acetylation of the aminobenzamide yields N-n-butyl-4-acetamidobenzamide.

Example 9 Preparation of N-n-propyl-4-acetamidobenzamide

The method of Example 3 is repeated using 4-nitrobenzoyl chloride andn-propyl amine in the amidation step. This yieldsN-n-propyl-4-nitrobenzamide (CPI1047).

Reduction of the nitrobenzamide with hydrazine yieldsN-n-propyl-4-aminobenzamide.

Acetylation of the aminobenzamide yieldsN-n-propyl-4-acetamidobenzamide.

Example 10 Preparation of N-1,2-dimethylpropyl-4-acetamidobenzamide

The method of Example 3 is repeated using 4-nitrobenzoyl chloride and1,2-dimethylpropyl amine in the amidation step. This yieldsN-1,2-dimethylpropyl-4-nitrobenzamide (CPI1085).

Reduction of the nitrobenzamide with hydrazine yieldsN-1,2-dimethylpropyl-4-aminobenzamide.

Acetylation of the aminobenzamide yieldsN-1,2-dimethylpropyl-4-acetamidobenzamide.

Example 11 Preparation of N-n-pentyl-4-acetamidobenzamide

The method of Example 3 is repeated using 4-nitrobenzoyl chloride andn-pentyl amine in the amidation step. This yieldsN-n-pentyl-4-nitrobenzamide (CPI1140).

Reduction of the nitrobenzamide with hydrazine yieldsN-n-pentyl-4-aminobenzamide.

Acetylation of the aminobenzamide yieldsN-n-pentyl-4-acetamidobenzamide.

Example 12 Preparation of N-2-methylbutyl-4-acetamidobenzamide

The method of Example 3 is repeated using 4-nitrobenzoyl chloride and2-methylbutyl amine in the amidation step. This yieldsN-2-methylbutyl-4-nitrobenzamide (CPI1146).

Reduction of the nitrobenzamide with hydrazine yieldsN-2-methylbutyl-4-aminobenzamide.

Acetylation of the aminobenzamide yieldsN-2-methylbutyl-4-acetamidobenzamide.

Example 13 Preparation of N-n-pentyl-2-acetamidobenzamide

The method of Example 3 is repeated using 2-nitrobenzoyl chloride andn-pentyl amine in the amidation step. This yieldsN-n-pentyl-2-nitrobenzamide (CPI1174).

Reduction of the nitrobenzamide with hydrazine yieldsN-n-pentyl-2-aminobenzamide.

Acetylation of the aminobenzamide yieldsN-n-pentyl-2-acetamidobenzamide.

Example 14 Preparation of N-tert-butyl-2,3-diacetamidobenzamide

The method of Example 3 is repeated using 2,3-dinitrobenzoyl chloride inthe amidation step. This yields N-tert-butyl-2,3-dinitrobenzamide.

Reduction of the nitrobenzamide with hydrazine yieldsN-tert-butyl-2,3-dinitrobenzamide.

Acetylation of the aminobenzamide yieldsN-tert-butyl-2,3-diacetamidobenzamide.

Example 15 Preparation of N-tert-amyl-2,4-diacetamidobenzamide

The method of Example 3 is repeated using 2,4-dinitrobenzoyl chlorideand tert-amyl amine in the amidation step. This yieldsN-tert-amyl-2,4-dinitrobenzamide.

Reduction of the nitrobenzamide with hydrazine yieldsN-tert-amyl-2,4-diaminobenzamide.

Acetylation of the aminobenzamide yieldsN-tert-amyl-2,4-diacetamidobenzamide.

Example 16 Preparation of N-tert-butyl-2,5-diacetamidobenzamide

The method of Example 3 is repeated using 2,5-dinitrobenzoyl chloride inthe amidation step. This yields N-tert-butyl-2,5-dinitrobenzamide.

Reduction of the nitrobenzamide with hydrazine yieldsN-tert-butyl-2,5-diaminobenzamide.

Acetylation of the aminobenzamide yieldsN-tert-butyl-2,5-diacetamidobenzamide.

Example 17 Preparation of N-tert-butyl-2,6-diacetamidobenzamide

The method of Example 3 is repeated using 2,6-dinitrobenzoyl chloride inthe amidation step. This yields N-tert-butyl-2,6-dinitrobenzamide.

Reduction of the nitrobenzamide with hydrazine yieldsN-tert-butyl-2,6-diaminobenzamide.

Acetylation of the aminobenzamide yieldsN-tert-butyl-2,6-diacetamidobenzamide.

Example 18 Preparation of N-tert-butyl-3,4-diacetamidobenzamide

The method of Example 3 is repeated using 3,4-dinitrobenzoyl chloride inthe amidation step. This yields N-tert-butyl-3,4-dinitrobenzamide.

Reduction of the nitrobenzamide with hydrazine yieldsN-tert-butyl-3,4-diaminobenzamide.

Acetylation of the aminobenzamide yieldsN-tert-butyl-3,4-diacetamidobenzamide.

Example 19 Preparation of N-tert-butyl-3,5-diacetamidobenzamide

The method of Example 3 is repeated using 3,5-dinitrobenzoyl chloride inthe amidation step. This yields N-tert-butyl-3,5-dinitrobenzamide.

Reduction of the nitrobenzamide with hydrazine yieldsN-tert-butyl-3,5-diaminobenzamide.

Acetylation of the aminobenzamide yieldsN-tert-butyl-3,5-diacetamidobenzamide.

Preparation of Pharmaceutical Compositions Example 20

The compound of Example 1 is admixed as a dry powder with a dry gelatinbinder in an approximate 1:2 weight ratio. A minor amount of magnesiumstearate is added as a lubricant. The mixture is formed into 240–270 mgtablets (80–90 mg of active benzamide) in a tablet press. If thesetablets were administered to a patient suffering from adopamine-associated neurodegenerative condition on a daily, twice dailyor thrice daily regimen they would slow the progress of the patient'sdisease.

Example 21

The compound of Example 2 is admixed as a dry powder with a starchdiluent in an approximate 1:1 weight ratio. The mixture is filled into250 mg capsules (125 mg of active benzamide). If these capsules wereadministered to a patient suffering from a dopamine-associatedneurodegenerative condition on a daily, twice daily or thrice dailyregimen they would slow the progress of the patient's disease.

Example 22

The compound of Example 3 is suspended in a sweetened flavored aqueousmedium to a concentration of approximately 50 mg/ml. If 5 mls of thisliquid material was administered to a patient suffering from adopamine-associated neurodegenerative condition on a daily, twice dailyor thrice daily regimen they would slow the progress of the patient'sdisease.

Example 23

The compound of Example 4 is admixed as a dry powder with a dry gelatinbinder in an approximate 1:2 weight ratio. A minor amount of magnesiumstearate is added as a lubricant. The mixture is formed into 450–900 mgtablets (150–300 mg of active benzamide) in a tablet press. If thesetablets were administered to a patient suffering from adopamine-associated neurodegenerative condition on a daily, twice dailyor thrice daily regimen they would slow the progress of the patient'sdisease.

Example 24

The compound of Example 14 is dissolved in a buffered sterile salineinjectable aqueous medium to a concentration of approximately 5 mg/ml.If 50 mls of this liquid material was administered to a patientsuffering from a dopamine-associated neurodegenerative condition such asParkinson's disease on a daily, twice daily or thrice daily regimen thisdose would slow the progress of the patient's disease.

It will be appreciated that any of the compounds of Formula II could beemployed in any of these representative formulations, and that any ofthese formulations could be administered in any of these manners so asto treat any of the neurodegenerative conditions described in thisspecification.

Parkinson's Disease Screening Methods

Dopamine Depletion Studies.

C57BL/6J mice were pretreated with either vehicle (1% methyl cellulose)or a drug (p.o.) 30 min before MPTP. MPTP was dissolved in isotonicsaline (0.9%) and given subcutaneously as a single dose of 15 mg freebase/kg body weight to produce a reduction in striatal dopamine to about0.5 nanomoles/mg protein. Groups of mice (n=8–10 per group) receivedeither vehicle plus saline, vehicle plus MPTP or drug plus MPTP. Seventytwo hours after receiving MPTP, mice were sacrificed using cervicaldislocation and the striata were excised. The tissue was homogenized in0.4 N perchloric acid, centrifuged, and the supernatant analyzed by highperformance liquid chromatography/electro-chemical detection (HPLC/ED)for dopamine levels. Supernatants were stored in a −90° C. freezerbetween the time of collection and analysis.

The drugs were combined with methyl cellulose and were homogenized inwater for dosing. The dosage amount ranged from 10 to 50 mg/kg forCPI1160, CPI1189 and CPI1234, and from 50 to 100 mg/kg for CPI1020.

The results of representative experiments are provided in Tables 1 and2. The results in Table 1 demonstrate that the compositions of thisinvention, as exemplified by CPI1160, CPI1189, and CPI1234 wereeffective in preventing dopamine depletion following MPTP challenge.

TABLE 1 Efficacy of CPI Compounds 1189, 1160, and 1234 at 30 mg/kg inthe 15 mg/kg MPTP Model. NANOMOLES DOPAMINE PER % NON-MPTP COMPOUND MGPROTEIN ± S.E.M. CONTROL methyl 0.72 ± .05 54.1 cellulose CPI1160 1.25 ±.05 93.9 CPI1234 1.02 ± .05 76.7 methyl 0.56 ± .07 36.4 celluloseCPI1189 1.37 ± .14 89.7

For comparison purposes the same tests were run on compositions based onCPI1020, a closely related benzamide compound. Results are shown inTable 2. At 50 mg/kg, CPI1189 offered complete protection from theneurotoxic action of MPTP (105% of control) while CPI1020 was not aseffective (65% of control).

TABLE 2 Comparison of the Efficacies of CPI1189 and CPI1020 at 50 mg/kgin the 15 mg/kg MPTP Model. NANOMOLES DOPAMINE PER COMPOUND MG PROTEIN ±S.E.M. CPI1020 0.58 ± .14 CPI1189 1.57 ± .11

1. A pharmaceutical composition comprising a benzamide compound of theformula

wherein R′ is a saturated alkyl of from 3 to 5 carbon atoms, each R isindependently —NO₂ or —NH₂ or NHCOCH₃, and n is 1 or 2, with thefollowing provisos: 1) when n is 1 and R is —NO₂ at the 4 position ofthe ring, R′ is not tert-butyl, iso-butyl, or propyl; 2) when n is 1 andR is —NO₂ at the 2 position of the ring, R′ is not iso-butyl or propyl;and 3) when n is 2 and R′ is tert-butyl and both Rs are —NO₂, the Rgroups are not at the 3 and 5 positions of the ring, in apharmaceutically acceptable carrier.
 2. The pharmaceutical compositionof claim 1 wherein the benzamide compound is an acetamidobenzamide ofthe formula

where R′ is a saturated alkyl of from 3 to 5 carbon atoms and n is 1 or2.
 3. The pharmaceutical composition of claim 2 wherein n is 1 and R′ istert-butyl or tert-amyl.
 4. The pharmaceutical composition of claim 3wherein the benzamide compound is N-tert-butyl-4-acetamidobenzamide. 5.The pharmaceutical composition of claim 3 wherein the benzamide compoundis selected from the group consisting ofN-iso-propyl-4-acetamidobenzamide, N-tert-amyl-4-acetamidobenzamide,N-tert-butyl-3-acetamidobenzamide, andN-methylcyclopropyl-4-acetamidobenzamide.
 6. The pharmaceuticalcomposition of claim 1 wherein R is —NH₂ or —NO₂.
 7. The pharmaceuticalcomposition of claim 6 wherein the benzamide compound is selected fromthe group consisting of N-iso-propyl-4-nitrobenzamide,N-tert-butyl-3-nitrobenzamide, N-tert-butyl-2-nitrobenzamide,N-n-butyl-4-nitrobenzamide, N-n-propyl-4-nitrobenzamide,N-tert-butyl-3,5-dinitrobenzamide, N-1-methylpropyl-4-nitrobenzamide andN-tert-butyl-3-aminobenzamide.
 8. The pharmaceutical composition ofclaim 1 wherein the benzamide compound is N-tert-butyl-4-aminobenzamide.9. The pharmaceutical composition of claim 1 wherein the carrier is anoral carrier or an injectable carrier.
 10. An acetamidobenzamidecompound of the formula

where R′ is a saturated alkyl of from 3 to 5 carbon atoms and n is 1 or2, with the proviso that, when n is 1 and R′ is either n-butyl orn-propyl, the acetamido group is not at the 2 position of the ring, whenn is 1 the acetamido group is not at the 3 position of the ring and,when n is 2, the acetamido groups are not at the 3 and 5 positions ofthe ring.
 11. N-tert-butyl-4-acetamidobenzamide.
 12. Aacetamidobenzamide compound selected from the group consisting ofN-iso-propyl-4-acetamidobenzamide, N-tert-amyl-4-acetamidobenzamide,N-tert-butyl-3-acetamidobenzamide, andN-methylcyclopropyl-4-acetamidobenzamide.
 13. A method for treating apatient suffering from a neurodegenerative condition comprisingadministering an effective neurodegenerative condition-treating amountof a pharmaceutical composition according to claim
 1. 14. The method ofclaim 13 wherein the neurodegenerative condition is one associated witha progressive loss of central nervous system function.
 15. The method ofclaim 13 wherein the neurodegenerative condition is adopamine-associated neurodegenerative condition.
 16. The method of claim15 wherein the dopamine-associated neurodegenerative condition isParkinson's disease.
 17. The method of claim 13 wherein theneurodegenerative condition is Alzheimer's disease.
 18. The method ofclaim 13 wherein the neurodegenerative condition is one associated witha progressive loss of central nervous system function due tomitochondrial dysfunction.
 19. The method according to claim 13 whereinthe pharmaceutical composition is administered orally, parenterally orby intravenous infusion.